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Dive into the research topics where Gjalt-Jorn Peters is active.

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Featured researches published by Gjalt-Jorn Peters.


Health Psychology Review | 2013

Threatening communication: a critical re-analysis and a revised meta-analytic test of fear appeal theory

Gjalt-Jorn Peters; Robert A. C. Ruiter; Gerjo Kok

Abstract Despite decades of research, consensus regarding the dynamics of fear appeals remains elusive. A meta-analysis was conducted that was designed to resolve this controversy. Publications that were included in previous meta-analyses were re-analysed, and a number of additional publications were located. The inclusion criteria were full factorial orthogonal manipulations of threat and efficacy, and measurement of behaviour as an outcome. Fixed and random effects models were used to compute mean effect size estimates. Meta-analysis of the six studies that satisfied the inclusion criteria clearly showed a significant interaction between threat and efficacy, such that threat only had an effect under high efficacy (d=0.31), and efficacy only had an effect under high threat (d=0.71). Inconsistency in results regarding the effectiveness of threatening communication can likely be attributed to flawed methodology. Proper tests of fear appeal theory yielded the theoretically hypothesised interaction effect. Threatening communication should exclusively be used when pilot studies indicate that an intervention successfully enhances efficacy.


International Journal of Psychology | 2014

Sixty years of fear appeal research: current state of the evidence.

Robert A. C. Ruiter; Loes T. E. Kessels; Gjalt-Jorn Peters; Gerjo Kok

Fear arousal is widely used in persuasive campaigns and behavioral change interventions. Yet, experimental evidence argues against the use of threatening health information. The authors reviewed the current state of empirical evidence on the effectiveness of fear appeals. Following a brief overview of the use of fear arousal in health education practice and the structure of effective fear appeals according to two main theoretical frameworks-protection motivation theory and the extended parallel process model-the findings of six meta-analytic studies in the effectiveness of fear appeals are summarized. It is concluded that coping information aimed at increasing perceptions of response effectiveness and especially self-efficacy is more important in promoting protective action than presenting threatening health information aimed at increasing risk perceptions and fear arousal. Alternative behavior change methods than fear appeals should be considered.


Health Psychology Review | 2016

A taxonomy of behaviour change methods: an Intervention Mapping approach

Gerjo Kok; Nell H. Gottlieb; Gjalt-Jorn Peters; Patricia Dolan Mullen; Guy S. Parcel; Robert A. C. Ruiter; Maria E. Fernandez; Christine M. Markham; L. Kay Bartholomew

ABSTRACT In this paper, we introduce the Intervention Mapping (IM) taxonomy of behaviour change methods and its potential to be developed into a coding taxonomy. That is, although IM and its taxonomy of behaviour change methods are not in fact new, because IM was originally developed as a tool for intervention development, this potential was not immediately apparent. Second, in explaining the IM taxonomy and defining the relevant constructs, we call attention to the existence of parameters for effectiveness of methods, and explicate the related distinction between theory-based methods and practical applications and the probability that poor translation of methods may lead to erroneous conclusions as to method-effectiveness. Third, we recommend a minimal set of intervention characteristics that may be reported when intervention descriptions and evaluations are published. Specifying these characteristics can greatly enhance the quality of our meta-analyses and other literature syntheses. In conclusion, the dynamics of behaviour change are such that any taxonomy of methods of behaviour change needs to acknowledge the importance of, and provide instruments for dealing with, three conditions for effectiveness for behaviour change methods. For a behaviour change method to be effective: (1) it must target a determinant that predicts behaviour; (2) it must be able to change that determinant; (3) it must be translated into a practical application in a way that preserves the parameters for effectiveness and fits with the target population, culture, and context. Thus, taxonomies of methods of behaviour change must distinguish the specific determinants that are targeted, practical, specific applications, and the theory-based methods they embody. In addition, taxonomies should acknowledge that the lists of behaviour change methods will be used by, and should be used by, intervention developers. Ideally, the taxonomy should be readily usable for this goal; but alternatively, it should be clear how the information in the taxonomy can be used in practice. The IM taxonomy satisfies these requirements, and it would be beneficial if other taxonomies would be extended to also meet these needs.


Health Psychology Review | 2015

Everything should be as simple as possible, but no simpler: towards a protocol for accumulating evidence regarding the active content of health behaviour change interventions

Gjalt-Jorn Peters; M. de Bruin; Rik Crutzen

There is a need to consolidate the evidence base underlying our toolbox of methods of behaviour change. Recent efforts to this effect have conducted meta-regressions on evaluations of behaviour change interventions, deriving each methods effectiveness from its association to intervention effect size. However, there are a range of issues that raise concern about whether this approach is actually furthering or instead obstructing the advancement of health psychology theories and the quality of health behaviour change interventions. Using examples from theory, the literature and data from previous meta-analyses, these concerns and their implications are explained and illustrated. An iterative protocol for evidence base accumulation is proposed that integrates evidence derived from both experimental and applied behaviour change research, and combines theory development in experimental settings with theory testing in applied real-life settings. As evidence gathered in this manner accumulates, a cumulative science of behaviour change can develop.


Alcoholism: Clinical and Experimental Research | 2016

Worldwide Prevalence of Fetal Alcohol Spectrum Disorders: A Systematic Literature Review Including Meta‐Analysis

Sylvia Roozen; Gjalt-Jorn Peters; Gerjo Kok; David Townend; Jan G. Nijhuis; Leopold Curfs

BACKGROUND Although fetal alcohol spectrum disorders (FASD) affect communities worldwide, little is known about its prevalence. The objective of this study was to provide an overview of the global FASD prevalence. METHODS We performed a search in multiple electronic bibliographic databases up to August 2015, supplemented with the ascendancy and descendancy approach. Studies were considered when published in English, included human participants, and reported empirical data on prevalence or incidence estimates of FASD. Raw prevalence estimates were transformed using the Freeman-Tukey double arcsine transformation so that the data followed an approximately normal distribution. Once the pooled prevalence estimates, 95% confidence intervals and prediction intervals were calculated based on multiple meta-analyses with transformed proportions using random effects models, these estimates were transformed back to regular prevalence rates. Heterogeneity was tested using Cochrans Q and described using the I(2) statistic. RESULTS Among studies that estimated prevalence in general population samples, considerable differences in prevalence rates between countries were found and therefore separate meta-analyses for country were conducted. Particularly high-prevalence rates were observed in South Africa for fetal alcohol syndrome (55.42 per 1,000), for alcohol-related neurodevelopmental disorder (20.25 per 1,000), and FASD (113.22 per 1,000), For partial fetal alcohol syndrome high rates were found in Croatia (43.01 per 1,000), Italy (36.89 per 1,000), and South Africa (28.29 per 1,000). In the case of alcohol-related birth defects, a prevalence of 10.82 per 1,000 was found in Australia. However, studies into FASD exhibited substantial heterogeneity, which could only partly be explained by moderators, most notably geography and descent, in meta-regressions. In addition, the moderators were confounded, making conclusions as to each moderators relevance tentative at best. CONCLUSIONS The worldwide pooled prevalence estimates are higher than assumed so far, but this was largely explained by geography and descent. Furthermore, prevalence studies varied considerably in terms of used methodology and methodological quality. The pooled estimates must therefore be interpreted with caution and for future research it is highly recommended to report methodology in a more comprehensive way. Finally, clear guidelines on assessing FASD prevalence are urgently needed, and a first step toward these guidelines is presented.


Psychology Crime & Law | 2006

False confessions in the lab: Do plausibility and consequences matter?

Robert Horselenberg; Harald Merckelbach; Tom Smeets; Dirk Franssens; Gjalt-Jorn Peters; Gwenny Zeles

Abstract The present paper describes three studies that examined false confessions in the laboratory. Studies 1 (N=56) and 2 (N=9) relied on the by now classic computer crash paradigm introduced by Kassin and Kiechel (Psychological Science, 7, 125–128, 1996). Study 3 (N=12) employed a novel paradigm in which undergraduate participants were falsely accused of exam fraud. Our data indicate that false confessions do occur, even when conditions become more ecologically valid. Furthermore, we explored whether individual differences in compliance, suggestibility, fantasy proneness, dissociation, and cognitive failures are related to false confessions. Of these, only fantasy proneness was associated with false confessions.


The European health psychologist | 2014

The alpha and the omega of scale reliability and validity: Why and how to abandon Cronbach’s alpha and the route towards more comprehensive assessment of scale quality

Gjalt-Jorn Peters

Health Psychologists using questionnaires rely heavily on Cronbach’s alpha as indicator of scale reliability and internal consistency. Cronbach’s alpha is often viewed as some kind of quality label: high values certify scale quality, low values prompt removal of one or several items. Unfortunately, this approach suffers two fundamental problems. First, Cronbach’s alpha is both unrelated to a scales internal consistency and a fatally flawed estimate of its reliability. Second, the approach itself assumes that scale items are repeated measurements, an assumption that is often violated and rarely desirable. The problems with Cronbach’s alpha are easily solved by computing readily available alternatives, such as the Greatest Lower Bound or Omega. Solving the second problem, however, is less straightforward. This requires forgoing the appealing comfort of a quantitative, seemingly objective indicator of scale quality altogether, instead acknowledging the dynamics of reliability and validity and the distinction between scales and indices. In this contribution, I will explore these issues, and provide recommendations for scale inspection that takes these dynamics and this distinction into account.


Health Psychology Review | 2017

Scale quality: alpha is an inadequate estimate and factor-analytic evidence is needed first of all

Rik Crutzen; Gjalt-Jorn Peters

ABSTRACT Cronbachs alpha is a commonly reported estimate to assess scale quality in health psychology and related disciplines. In this paper, we argue that alpha is an inadequate estimate for both validity and reliability – two key elements of scale quality. Omega is a readily available alternative that can be used for both interval and ordinal data. More importantly, we argue that factor-analytic evidence should be presented before assessing the internal structure of a scale. Finally, pointers for readers and reviewers of manuscripts on making judgements about scale quality are provided and illustrated by examples from the field of health psychology.


Journal of Adolescent Health | 2011

An Artificially Intelligent Chat Agent That Answers Adolescents' Questions Related to Sex, Drugs, and Alcohol: An Exploratory Study

Rik Crutzen; Gjalt-Jorn Peters; Sarah Dias Portugal; Erwin M. Fisser; Jorne J. Grolleman

PURPOSE The aim of this study was to investigate if and how an artificially intelligent chat agent (chatbot) that answers questions about sex, drugs, and alcohol is used and evaluated by adolescents, especially in comparison with information lines and search engines. METHODS A sample of 929 adolescents (64% girls, mean age = 15), varying in urbanization level and educational level, participated in this study. Use of the chatbot was objectively tracked through server registrations (e.g., frequency and duration of conversations with the chatbot, the number and topics of queries), and a web-based questionnaire was used to evaluate the chatbot (e.g., the perception of anonymity, conciseness, ease of use, fun, quality and quantity of information, and speed) and to compare it with information lines and search engines. RESULTS The chatbot reached high school attendees in general and not only adolescents with previous experience related to sex, drugs, or alcohol; this is promising from an informed decision-making point of view. Frequency (M = 11) and duration of conversations (3:57 minutes) was high and the chatbot was evaluated positively, especially in comparison with information lines and search engines. CONCLUSION The use of chatbots within the field of health promotion has a large potential to reach a varied group of adolescents and to provide them with answers to their questions related to sex, drugs, and alcohol.


International Journal of Psychology | 2014

Threatening communication: A qualitative study of fear appeal effectiveness beliefs among intervention developers, policymakers, politicians, scientists, and advertising professionals

Gjalt-Jorn Peters; Robert A. C. Ruiter; Gerjo Kok

Threatening communication is a widely applied method in behavior change interventions, which at the same time has been heavily criticized in the psychological literature. The current paper describes a study of the reasons for this persistent wide application of threatening communication. We conducted qualitative interviews with 33 key actors in behavior change intervention development in The Netherlands. Specifically, we interviewed intervention developers, policymakers, politicians, scientists, and advertising professionals. The interviews were transcribed and subsequently coded using NVivo. We found that participants most closely involved with the actual intervention development were generally convinced that threatening information was to be prevented, but often did not understand the exact processes involved. They were often under the impression that rather than a potent efficacy enhancing element, a behavioral suggestion would suffice to prevent threatening communication from backfiring. As participants were further removed from the actual intervention development, they generally tended to be more in favor of threatening communication. The main reasons for use of threatening information were to attract attention or prompt self-reflection through confrontation, because target population members were assumed to like threatening information and respond rationally to increased risk perceptions by changing their behavior, or simply because no alternatives were available. In addition, intervention developers frequently had to deal with supervisors or funders who preferred threatening communication. Thus, when communicating with practitioners, it seems fruitful to provide them with a toolbox of evidence-based behavior change methods that promote adaptive, rather than maladaptive, behavior; to promote basing interventions on the most relevant behavioral determinants as identified by determinant analyses; and to equip intervention developers with the tools to persuade other key stakeholders that fear is a bad counselor.

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Gerjo Kok

Maastricht University

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Leopold Curfs

Maastricht University Medical Centre

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Sylvia Roozen

Maastricht University Medical Centre

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